Photographic developer for use at high temperatures



Patented M... 10, 1932 V UNITED STATES PATENT} ori ice .I

I} 1,857,515} ft acwnu. E. manna, or ROCHESTER, NEW Yonx, ASSIGNOR To EASTMAN xonA'kY COMPANY, or nocnasrna, new YORK, A ,coaronarron or nnw "max I :PHoToonArrno nnvnnornn FOB use AT HIGH TmrEaATuBns No Drawing.

This invention relates to a photographic developer, especially to one capable of use at relatively high temperatures and more particularly to one which contains a well-known 5 hardening agent, namely, formalin, but which contains a developing agent such 'that the developer gives no appreciable fog at the temperatures used. This is a specificapplication of the ideas broadm ly claimed in the co-pending application Serial No. 435,954 filed March 14, 1930, by John I. Crabtree and John F. Ross.

An object of the invention is to avoid excessive fog when formalin is used to harden .15 the film.

- The use of formalin as a hardening agent in developers or other photographic baths, especially for use in the troplcs or at relatively high temperatures, has been known for many years, there being many references to its use in the literature and text books of photography. In the art of photographic developing, temperatures very much in excess of 70 degrees Fahrenheit are usually termed high temperatures and the term is so used here. When formalin is used with any of the ordinary developers for high temperature work it usually produces a heavy fog or veiling of the image which is, of course, ob-

jectionable. This cannot be overcome by the use of any of the agents usually employed for reducing fog, such as potassium bromide, and the use of formalin for high temperature development has therefore been greatly restricted. This is particularly true of alkaline developing solutions.

I have found that by using only a certain class of developing agents in a formula for a photographic developer including formalin that no appreciable fog is produced even if the solution is alkaline. The developing agents which I use are the halogen substituted hydroquinones, such as nionochlorhydroquinone, dichlorhydroquinone, trichlor hydroquinone, monoand di-brom hydroquinone and iodo-hydroquinone. It is only necessary to make up a suitable developer containing these substances together with formalin to prepare a developer giving the desired results. Development, of course, is

Application filed February 12, 1980. Serial K0. 427,944.

carried out in the usual manner after which v the plate or film is washed and fixed, preferably in a hardening-fixing Bath of a. well known type.

In carrying out my invention the formaldehyde may be used in the form of the 40% solution sold on the market or in the form of the dry powdered trioxymethylene which with water under the conditions employed yields formaldehyde. Two formulae which are illustrative of a number which may be used are:

Formula 1 Dichlorhydroquinone 5.0 grams Sodium sulplnte,anhydrous 25.0 grams Sodium carbonate, anhydrousn- 25. 0 grams Potassium bromide; "L- 1. 5 grams 40% formaldehyde 12. 5 co. Water to 1. 0 litre Formuig 2 While particularly useful at higher temperatures the advantages are also inherent whatever the temperature. F ormalin is not, however, often used at low temperatures- I consider as within my invention all equivalents and modifications coming within the scope of the appended claims. I

\Vhat I claim is:

1. A photographic developer substantially free from fogging efiects when used at hig temperatures including formalin and a halo-' gen substituted hydroquinone.

2. A photographic developer substantially free from fogging effects when used at high temperatures including formalin and a chlorhydroquinone.

3. A photographic developer substa-ntiall free from fogging effects when used at high temperaturesincluding formalin and mono chlor-hydroquinone.

4. A photographic developer substantially free from fogging effects when used at high temperatures including formalin, an" alksili and a halogen-substituteq hydroquinone.

5. A photqgraphic developer substantiall iree from fogging efiects when used'at hig 5 temperatures ancluding formalin, an alkali and; chlor-hy-droquinone. Y 6. A'photographic-developer substantiall free from fogging "effects" when 'u sd at big temperatures including iformalimanalkaliv 1 andmono-chlor-hydroquinon.

Signed at Rochester, New Y0rk,-this 1st day of February, 1930. LOWELL E. MUEHLER. 

